method for forming pattern onto article during injection molding thereof

ABSTRACT

A method for forming a pattern onto an article during injection molding thereof. A pattern-bearing film is heated and softened by a heating board. The softened pattern-bearing film is transferred to the cavity surface of a female mold. Thereafter, the female mold and a male mold are closed. Then, a molten resin is injected into the cavity. When a pattern-bearing film is brought in contact with and heated by the heating board, marks or impressions of air blow holes on the surface of the heating board remain on the pattern-bearing film. To prevent the formation of these marks or impressions, a square-shaped holding frame is fixed on the surface of the heating board. The peripheral portion of the pattern-bearing film is held on the surface of the holding frame. Thus, while the pattern portion of the pattern-bearing film is spaced apart from the surface of the heating board, the film is heated. To keep the pattern-bearing film uniformly spaced from the surface of the heating board, air is supplied to the inside of the holding frame.

This is a Continuation of application Ser. No. 08/369,491 filed Jan. 6,1995, now U.S. Pat. No. 5,603,889, which is a divisional of applicationSer. No. 08/051,365 filed Apr. 23, 1993 now U.S. Pat. No. 5,415,536.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for forming a pattern onto anarticle during an injection molding thereof and an apparatus for thesame, for preventing impressions of a heating board from remaining onthe surface of the molded article or molding.

2. Description of the Related Art

Conventionally, as decorative patterning methods for three-dimensionalsolid moldings, a laminate method and a transfer printing method areknown. In the laminate method, after a film on which a pattern has beenprinted is shaped or concurrently therewith, the film is adhered to asubstrate, or while or after the film is shaped, the film is filled witha resin. On the other hand, in the transfer printing method, only apattern ink of a film on which the pattern has been printed istransferred to a molded article or molding.

As a transfer printing method, a method disclosed in Japanese PatentLaid-Open Publication Serial No. SHO 62-196113, published on Aug. 29,1987 is known. In this method, as will be described later, a heatingboard which absorbs a pattern-bearing film thereon is moved into a spacebetween a male mold and a female mold which are spaced apart from eachother by a predetermined distance. Then the pattern-bearing film heatedby the heating board is vacuum absorbed to the inner surface of thefemale mold. Thereafter, the heating board is retreated to the outsideof the space between the male mold and the female mold. Next, the malemold and the female mold are clamped or closed. In the cavity defined bythese molds, a molten resin is injected to form a molded article. Thus,the pattern-bearing film is attached to the surface of the molded resinarticle.

However, in this method, when the pattern-bearing film is absorbed tothe heating board, air is caught between the heating board and thepattern-bearing film. This air remains as air bubbles. Thus, thepattern-bearing film is not uniformly heated. In addition, marks orimpressions of vacuum holes defined on the heating board remain on thesurface of the final molding having the pattern-bearing film absorbedthereby. Thus, the appearance of the molding is adversely affected.

To solve this problem, a method as disclosed in Japanese PatentLaid-Open Publication Serial No. HEI 3-96320 has been proposed. In thismethod, a pattern-bearing film absorbing surface of a heating board isformed of an uneven surface having a large number of concave and convexportions. With these concave and convex portions, a large number ofpassageways are formed so as to allow the air to escape. In this method,although air bubbles may be prevented, if the pattern-bearing film isthin, the impressions of the concave and convex portions and the vacuumholes remain on the pattern-bearing film. Thus, the appearance of themolding is deteriorated.

SUMMARY OF THE INVENTION

The present invention is made from the above-mentioned point of view. Anobject of the present invention is to provide a method for forming apattern onto an article during an injection molding thereof and anapparatus for the same for preventing the impressions from remaining onthe surface of a molding with a pattern.

According to one aspect of the present invention, the above object isaccomplished by a method for forming a pattern onto an article during aninjection molding thereof, comprising the steps of moving apattern-bearing film to a molding position where a male mold and afemale mold are opposed, heating the pattern-bearing film by a heatingboard so as to soften it, transferring the pattern-bearing film to aninternal surface of the female mold so as to contact the pattern-bearingfilm with the internal surface, retracting the heating board from themolding position, clamping the male mold and the female mold, injectinga molten resin into a cavity defined by the male mold and the femalemold so as to form a molded article, and adhering the pattern-bearingfilm to the surface of the molding, wherein the improvement comprisesthe step of holding only an outer peripheral portion of thepattern-bearing film in a spaced relation to a heating surface of theheating board so as to prevent the pattern-bearing film from directlycontacting the heating surface.

According to another aspect of the present invention, the above objectis accomplished by an apparatus for forming a pattern onto an articleduring an injection molding thereof, comprising means for feeding apattern-bearing film to a molding position where a male mold and afemale mold are opposed, heating board means for heating thepattern-bearing film so as to soften it, the heating board having aheating surface and being movable into and away from a space between themale mold and the female mold, means for transferring thepattern-bearing film to an internal surface of the female mold so as tocontact the pattern-bearing film with the internal surface, means forcausing the male mold and the female mold with the pattern-bearing filmtherein to approach each other so as to form a closed molding cavity,and resin injecting means for injecting a molten resin into the cavityso as to form a molded article and for adhering the pattern-bearing filmto the surface of the article, the improvement comprising holding framemeans fixed on the heating surface of the heating board and raised fromthe heating surface, for holding only an outer peripheral portion of thepattern-bearing film over the heating surface so as to prevent thepattern-bearing film from directly contacting the heating surface.

According to the present invention, after the pattern-bearing film isheated by the heating board, marks or impressions of the air blowingholes of the heating board do not remain on the pattern-bearing filmsince the pattern-bearing film is apart from the surface of the heatingboard.

These and other objects, features and advantages of the presentinvention will become more apparent in light of the following detaileddescription of best mode embodiments thereof, as illustrated in theaccompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view schematically showing the overall construction ofan embodiment according to the present invention;

FIG. 2 is a partial sectional side view of a heating board according tothe embodiment;

FIG. 3 is a front view of the heating board;

FIG. 4 is an enlarged sectional view showing the heating board and aholding frame;

FIG. 5 is a side view showing a pattern-bearing film held by the heatingboard and the holding means according to the embodiment;

FIG. 6 is a perspective view showing the holding frame according to theembodiment;

FIG. 7 is a sectional view showing the pattern-bearing film absorbed orsucked by a female mold;

FIG. 8 is a timing chart showing the operation according to theembodiment;

FIGS. 9 through 11 are side views showing successive operational stepsof another embodiment of the present invention;

FIG. 12 is a partial left side view, partly in section, of a female moldshown in FIG. 11;

FIGS. 13 through 16 are side views showing further successiveoperational steps of the other embodiment;

FIG. 17 is an enlarged partial view showing a next step of FIG. 16; and

FIGS. 18 through 22 are sectional views showing successive operationalsteps of a known apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In order to make clear novel features of the embodiments of the presentinvention and to make clear attendant problems of the prior art, anapparatus for forming a pattern onto an article during an injectionmolding thereof, described in Japanese Patent Laid-Open PublicationSerial No. SHO 62-196113, will be explained with reference to FIGS. 18through 22.

As shown in FIG. 18, a male mold 51 and a female mold 53 are oppositelydisposed. The male mold 51 is stationary, while the female mold 53 ismovable by a ram 52 in the left and right directions toward and awayfrom the male mold 51. A heating board 54 is movable over a rail 55 intoand away from the space between the molds 51 and 53.

At the center of the male mold 51, an injection unit 56 is disposed. Theinjection unit 56 injects a pressured molten resin. The pressured moltenresin is supplied to a cavity of the female mold 53 through an injectiongate 57 disposed in the male mold 51.

The operation of the above-described apparatus is as follows.

As shown in FIG. 18, a strip-shaped pattern-bearing film F is fed to aheating surface 54a of the heating board 54 by a feed unit (not shown inthe figure). Thereafter, the pattern-bearing film F is cut into a piecewith a size corresponding to one molded article. The resultant piece offilm F is sucked through vacuum holes 54b defined in the heating board54. Thus, the film F is brought into close contact with the heatingsurface 54a. Thereafter, as shown in FIG. 19, the heating board 54,while transferring heat to the pattern-bearing film F, is moveddownwardly as viewed until it comes to an opposite position of thefemale mold 53. Next, the ram 52 is advanced rightwardly whereby an endsurface 53a of the female mold 53 and the heating board 54 clamp thepattern-bearing film F therebetween. Then, as shown in FIG. 20, thepattern-bearing film F is sucked by vacuum holes 53b formed in thefemale mold 53. Thus, the pattern-bearing film P is absorbed and broughtin close contact with an internal molding surface of the female mold 53.Thereafter, as shown in FIG. 21, the heating board 54 is moved over therail 55 away from the molds. As a result, the male mold 51 and thefemale mold 53 are opposed. In this state, the ram 52 is furtheradvanced rightwardly. Thus, as shown in FIG. 22, the male mold 51 andthe female mold 53 are brought into mutual abutment. In this state, amolten resin is supplied from the injection unit 56 into the cavitythrough the injection gate 57. Thus, a molding or molded article isformed.

However, in the above method, when the pattern-bearing film F iscontacted with the heating board 54, if "air bubbles" are caught, thepattern-bearing film F will not be uniformly heated. In addition, thevacuum holes 54b on the heating board 54 will be impressed to the film Fand deteriorate the appearance thereof.

To solve such problems, Japanese Patent Laid-Open Publication Serial No.HEI 3-96320 proposes forming an uneven surface on the heating board soas to communicate each vacuum hole 54b with passageways formed in theuneven surface.

However, even when such uneven surface is provided, uneven marks orimpressions still remain on the molded article depending on thethickness of the pattern-bearing film. Thus, the appearance of themolded article becomes poor.

According to the present invention, such problems can be solved.Embodiments of the present invention will now be described withreference to the drawings.

FIG. 1 is a side view schematically showing the overall construction ofan apparatus for forming a pattern onto an article during an injectionmolding thereof. A male mold 1 is fixed on a mounting board 3. The malemold 1 is opposed to a female mold 2. An injection nozzle 5 is disposedon the male mold 1 to communicate with an injection gate 4. The femalemold 2 is fixed to a ram 7 through a movable board 6. With forward andbackward traveling operation of the ram 7, the female mold 2 advances toand retreats from the male mold 1. In addition, the female mold 2 isprovided with an air exhaust hole 8 through which air in the female mold2 is exhausted to the outside by a vacuum pump (not shown in thefigure).

At a position spaced apart from the outer peripheries of the male mold 1and the female mold 2 by a predetermined distance, a heating board 9 isdisposed. The position where the heating board 9 is disposed willhereinafter be referred to as the standby position. On the other hand,the position where the male mold 1 and the female mold 2 are opposed andthe heating board 9 is moved therebetween will hereinafter be referredto as the loading position. The heating board 9 can be laterallytravelled between the standby position and the loading position by adrive means. The drive means comprises a feed screw 33c and a motionconversion member 33b in the form of a nut. The motion conversion memberhas female threads which are engaged with the male threads of the feedscrew 33c so as to convert the rotation of the feed screw into linearmotion along the feed screw 33c. In the figure, the standby position isdenoted by the solid line, while the loading position is denoted by thetwo-dashed line. At the standby position, the heating board 9 absorbs apattern-bearing film X and travels to the loading position so as toplace the film X between the male mold 1 and the female mold 2. Whilethe heating board 9 is travelling from the standby position to theloading position, it heats the absorbed pattern-bearing film X so as toproperly soften it. Thereafter, the pattern-bearing film X is releasedat the loading position and absorbed to an internal cavity surface 2a ofthe female mold 2. In order to carry out this operation, the heatingboard 9 has means for holding the pattern-bearing film X on the sidefacing the female mold 2.

FIGS. 2 and 3 show the construction of the heating board 9 in detail.

The heating board 9 has integral layers of a heating plate 10, a linerplate 11, a heater panel 12, and an insulation plate 13 which aredisposed in this order. To the heating plate 10 is absorbed thepattern-bearing film X. On the front surface of the heating plate 10, asquare-shaped holding frame 14 is provided which is one of essentialelements of the present invention. The heating board 9 is mounted to asupport member 15 so as to be moved by solenoids 16. With the operationof the solenoids 16, the heating board 9 is moved in the directionperpendicular to the loading direction. The solenoids 16 cause theheating board 9 to advance to and retreat from the female mold 2.

The heating plate 10 of the board 9 is made of a metal with high heattransfer characteristic. In the area where the heating plate 10 issurrounded by a peripheral wall 14a of the holding frame 14, a largenumber of small air blowing holes 17 are formed in an array at intervalsof a predetermined pitch. The air blowing holes 17 pass from the frontto rear surfaces of the heating plate 10. With the heating plate 10 andthe peripheral wall 14a of the holding frame 14, a recess 14b, which isan essential feature of the present invention, is formed as also shownin FIG. 5. When a ceramic layer is formed on the front surface of theheating plate 10, radiant heat efficiency will be improved. The linerplate 11, which is disposed behind the heating plate 10, is composed ofa metal plate with a high heat transfer characteristic. The liner plate11 has a surface which is in contact with the rear surface of theheating plate 10. The surface has grooves 18 distributed therein throughwhich compressed air is supplied to the air blowing holes 17. An airpassageway 19 is provided at the center of the liner plate 11. The airpassageway 19 passes through the liner plate 11. The air passageway 19also passes through the center of the heater panel 12 and the insulationplate 13. The air passageway 19 is open at the rear surface of theinsulation plate 13. The open portion of the air passageway 19 isconnected to an air hose 20. The air hose 20 can be connected to eithera low pressure compressor 22 or a high pressure compressor 23 by athree-way switching valve 21.

The heater panel 12 has a number of heater wires 24. The heater wires 24are connected to a lead cable (not shown in the figure) which supplieselectricity. The insulation plate 13 serves to effectively transfer theheat generated by the heater wires 24 toward the heating plate 10.

As shown in FIG. 3 and FIG. 4 (which is an enlarged view of the portiondenoted by symbol IV in FIG. 2), a seal ring receiving groove 25 isformed along the peripheral wall 14a of the holding frame 14. A sealring 26 is fitted in the groove 25. With the seal ring 26, air leakagecan be prevented. In addition, in the vacuum molding operation, thepattern-bearing film can be prevented from being deviated from apredetermined position.

As shown in FIGS. 1 and 2, at the standby position of the heating board9, a film suppressing device 31 is provided in opposition thereto. Thefilm suppressing device 31 includes a square-shaped film suppressingframe 32 (shown in FIG. 6), an air cylinder 33a, and the above-mentioneddrive mechanism 33b. The air cylinder 33a operates to move the filmsuppressing frame 32 along the heating board 9. The drive mechanism 33boperates to move the suppressing frame 32 so that it advances to andretreats from the heating board 9 and the female mold 2. The suppressingframe 32 operates to suppress and hold the pattern-bearing film X in aperfectly non-contact state. The film suppressing device 31 has a chuckdevice 34 and a cutter device 35. The chuck device 34 pulls thepattern-bearing film X to the position between the heating board 9 andthe film suppressing frame 32 while the film suppressing frame 32 isapart from the heating board 9. The cutter device 35 cuts the pulledpattern-bearing film X to have a predetermined size. The cutter device35 is driven by an air cylinder 36.

The pattern-bearing film X is initially in the form of a strip on whichparticular patterns Y (see FIG. 3) are printed at predeterminedintervals. The pattern-bearing film X is wound in a roll shape and heldon a supply and holding device (not shown in the figure). The chuckdevice 34 catches the end of the pattern-bearing film X and pulls it fora predetermined distance from the film supply and holding device to thefront surface of the heating board 9. The length of the pattern-bearingfilm X to be pulled at a time is equivalent to the length of the patternsupplied on the front surface of the heating board 9 for one shot of theresin molding. A pattern-bearing film section with the pattern Y thereonis pressed toward the heating board 9 by the film suppressing frame 32.While the film is being suppressed and held, the peripheral wall 14a ofthe holding frame 14 of the heating board 9 supports the peripheralportion of the pattern-bearing film X so as to tension the film toeliminate any wrinkles. In this state, the cutter device 35 cuts thepattern-bearing film X so as to separate the held pattern-bearing filmsection from the succeeding part of the film X.

Next, with reference to the timing chart shown in FIG. 8, an example ofthe operation of the apparatus for forming a pattern onto an articleduring an injection molding thereof will be described.

When the heating board 9 shown in FIGS. 1 and 2 is placed in the standbyposition and the film holding frame 32 is apart from the heating board9, the chuck device 34 pulls the pattern-bearing film X to feed it tothe front position of the heating board 9 (step S1). The pulledpattern-bearing film X is pressed to the front surface of the holdingframe 14 of the heating board 9 by the film suppressing frame 32 (stepS2). Meanwhile, by the three-way switching valve 21, the air passageway19 and the grooves 18 are connected to the low pressure compressor 22.Air at low pressure supplied from the low pressure compressor 22 isblown in a small quantity out of the air blowing holes 17 in the heatingplate 10. Thereafter, the cutter device 35 cuts the film (steps S3 andS4). The blowing amount from the blowing holes 17 should be adjusted sothat the pattern-bearing film X is maintained in a spaced parallelrelation with the heating board 9 without deviation from the holdingframe 14 and without being loosened. When not necessary, the air blowingmay be omitted.

Thereafter, the film suppressing frame 32 and the heating board 9 aremoved into the space between the male mold 1 and the female mold 2.Thus, the pattern-bearing film X is loaded to the front surface of thefemale mold 2. Thereafter, while the vacuum pump 30 and the low pressurecompressor 22 are connected through the three-way switching valves 21and 29, respectively, the pattern-bearing film X is maintained parallelto the heating board 9 without looseness while being held on theperipheral wall 14a of the holding frame 14. Thus, the pattern-bearingfilm X has been loaded while it is spaced apart from the surface of theheating plate 10 in a non-contact state. Since the heating plate 10 isheated by the heater wires 24, the pattern-bearing film X is continuallyheated and softened by radiant heat from the heating plate 10 and/or byheat transfer through air until the loading of the pattern-bearing filmX has been completed. Since the pattern-bearing film X should besoftened by heat, it is composed of a thermoplastic resin film. Thedegree of the softening should be higher than the softening temperatureof the thermoplastic resin and less than the melting temperaturethereof.

As described above, the cutter device 35 is operated to cut thepattern-bearing film X after the film suppressing frame 32 has pressedthe pattern-bearing film X to the front surface of the holding frame 14,and thereafter the pattern-bearing film X is heated and softened by theheating plate 10. This is advantageous because when the pattern-bearingfilm X is heated, the heated section of the film X has already beenisolated by cutting from the rest of the film extending from the supplyroll to the heated section of the film, and the heated section of thefilm which is being subjected to heat and stress is prevented frominfluencing the rest of the film extending from the supply roll to theheated section. If the rest of the film extending from the supply rollwere connected continuously with the heated section, the rest of thefilm would be adversely influenced by the heat and stress in the heatedsection and be distorted, slackened, stretched, strained or wrinkled. Itis apparent that such adverse influence on the rest of the film willcause a poor pattern forming on articles in the succeeding patternforming steps. The use of the supply roll of the pattern-bearing film inthe form of a strip is advantageous in that conveyance of thepattern-bearing film is easy and can be made efficiently so thatproductivity of articles applied with surface patterns is improved.

After the pattern-bearing film X is loaded, the solenoids 16 areenergized whereupon the heating board 9 is moved toward the female mold2 (step S5). As shown in FIG. 7, the heating board 9 finally abutsagainst the female mold 2 (step S6). At this point, air is exhaustedfrom the closed inner space of the female mold 2 through the air exhausthole 8. Thus, the inside of the female mold 2 becomes vacuum (step S7).Thereafter, by the switching operations of the three-way switchingvalves 21 and 29, the high pressure compressor 23 is connected to theair passageway 19 in the heating board 9. Thus, compressed air at highpressure is blown out from the air blowing holes 17 (step S8). The airblown and the vacuum inside the female mold 2 cause the pattern-bearingfilm X to be transferred to the cavity surface 2a of the female mold 2.In other words, the pattern-bearing film X is caused to contact with themold in the vacuum state. Thereafter, the heating board 9 is retractedfrom the female mold 2 to the standby position along with the filmsuppressing frame 32 (step S9). Thus, by the operation of the ram 7, thefemale mold 2 and the male mold 1 are moved to a closed state. In thismold closing state, a molten resin is supplied into the cavity betweenthe male mold 1 and the female mold 2. Thus, the resin is molded (stepS10) and the pattern Y is transferred and printed onto the resinmolding.

During the process in which the pattern-bearing film X is loaded betweenthe male mold 1 and the female mold 2 while the film X is being absorbedand heated by the heating board 9, only the peripheral portion of thepattern-bearing film X is pressed to the peripheral wall 14a of theholding frame 14. Thus, the pattern portion Y is in a floating statewithin the recess 14b defined in the holding frame 14. In addition,since air at low pressure causes the pattern-bearing film X to floatfrom the heating plate 10, marks or impressions of the air blowing holes17 which are open on the heating plate 10 do not remain on the pattern Yof the pattern-bearing film X. Therefore, uneven marks do not remain onthe surface of the resin molding. Furthermore, the gloss of the resinmolding does not undergo undesirable variation.

It should be noted that the above-described method is a mere example andthat if the pattern-bearing film is heated in a non-contact state whileit is held and absorbed to the peripheral wall, any other method may beused.

Next, a method of attaining positional correspondence of thepattern-bearing film and the mold and a method of determining the timingof heating the pattern-bearing film and the timing of feeding thepattern-bearing film to the mold will be described.

Positional correspondence of Pattern-Bearing Film and Mold

When a large number of moldings having the same pattern and the sameshape are produced, the pattern-bearing film X is positioned relative tothe heating board 9 so that the positions of each pattern Y and theheating board 9 will match at each shot. When the relative positions ofthe heating board 9 and the female mold 2 which are to be contacted arepredetermined, the same relation of positions of the pattern Y and themold and the same relation of the pattern Y and the molding can beattained at each shot.

As a method for attaining positional correspondence, a known method maybe used. For example, when the printing of the pattern of thepattern-bearing film is performed, registration marks (for example,cross-shaped marks) for attaining positional correspondence with respectto the film feeding direction and the width direction are printed atpredetermined positions relative to the pattern. In addition, atpredetermined positions of the injection molding apparatus, for exampleat upstream positions of the mold, sensors (for example, photoelectrictubes) which detect the registration marks in both the feed directionand the width direction are provided. Moreover, there are provided driveunits (for example, stepping motors) which are controlled in response todetection signals from the sensors.

At step S1, when the feed direction sensor detects the registration markfor the feed direction, the drive unit which drives the chuck device 34in the feed direction is stopped. Thereafter, the chuck device 34 isdriven in the width direction. When the width direction sensor detectsthe width direction registration mark, the drive unit which drives thechuck device 34 in the width direction is stopped. Thus, the relativeposition of the pattern to the heating board 9 attains the predeterminedposition. Thereafter, the operation of the step 2 is performed.

When the relative position of the pattern and the molding need not beequally set at each shot, the above stated positional correspondencesystem may be omitted.

Timing of Heating of Pattern-Bearing Film and Timing of Feeding Film toMold

In the above-described embodiment, the pattern-bearing film X which isto be contacted with the heating board 9 is fed to the mold while thepattern-bearing film X is being heated. To shorten the molding cycle,this embodiment is suitable. However, another example where thepattern-bearing film X is heated after it has been fed to the mold maybe used.

As an example of the "laminate film" for the above-mentionedpattern-bearing film, a thermoplastic resin such as acrylic resin,acrylonitrile-butadiene-styrene copolymer (ABC), or polyvinyl chloridewith a pattern printed may be used.

As an example of the above-mentioned transfer printing film, such amaterial may be used where a transfer printing layer composed of atransparent protection layer, a pattern layer, and an adhesive layer isformed over a releasable substrate film such as biaxial stretchingpolyethylene terephthalate resin or polypropylene.

From the viewpoint of the three-dimensional contour-followingcharacteristic (molding characteristic) required in the process forinjection-molding articles with simultaneous forming of patterns andfrom the viewpoint of durability (such as wearing resistance) of thesurface of the pattern, "a resin which will become a non-tackythermoplastic solid even in a non-crosslinked state after drying of thediluting solvent" may be used. Such resin is disclosed in JapanesePatent Laid-Open Publication Serial Nos. SHO 61-69487 and SHO 60-161121.An example of the film substrate material of the laminate film or thetransparent protection layer of the transfer film is a substance where anon-tacky thermoplastic copolymer such as acrylic resin with a glasstransition temperature of 0° to 250° C. is added with a polymerizablecrosslinkable radical such as acryloyl radical or meta-acryloyl radical.

The substance in a state before polymerization or crosslinking istransferred or laminated to the surface of the injected resin molding.Thereafter, with radiation of ultraviolet rays or electric beam, theresultant laminate is crosslinked so that it is hardened.

Next, with reference to FIGS. 9 through 17, another example ofpositioning, heating, and feeding a pattern-bearing film will bedescribed. In the state shown in FIG. 9, a male mold 1 and a female mold2 are open. A heating board 9 and a film holding frame 32 are disposedoutside the region of the male mold 1 and the female mold 2 (namely, ata standby position). A pattern-bearing film X is wounded on a filmsupply and holding device so that it can be supplied to a holding frame14.

Thereafter, a chuck device 34 catches the end of the pattern-bearingfilm X and pulls it across the male mold 1 and the female mold 2 untilit covers the entire cavity of the female mold 2. When necessary, thepattern of the pattern-bearing film X may be adjusted to exactlycoincide with the female mold 2 according to the above-mentioned method.

Next, as shown in FIG. 10, the film suppressing frame 32 is moved fromthe standby position disposed outside the region of the male mold 1 andthe female mold 2 to a position opposed to the female mold 2 with thepattern-bearing film X therebetween. Thereafter, the suppressing frame32 is adjusted to coincide with a film suppressing frame fitting groove2b on a parting surface of the female 2. The groove 2b is defined sothat it surrounds the cavity surface.

Next, as shown in FIG. 11, the film suppressing frame 32 is pressed intothe film suppressing frame fitting groove 2b with the pattern-bearingfilm X interposed therebetween. Thus, the pattern-bearing film X iscontacted to the female mold 2. At this point, it is preferred that theouter surface of the film suppressing frame 32 is level with the partingsurface of the female mold 2 after the fitting is completed. However, asshown in the figure, when a film suppressing frame fitting groove 1a isformed on the peripheral portion of the male mold 1 so that it isopposed to the film suppressing frame fitting groove 2b of the femalemold 2, it is not necessary to cause the outer surface of the filmsuppressing frame 32 to be level with the parting surface. Rather, thefilm suppressing frame 32 may protrude so that a peripheral portion 14aof the holding frame 14 can be easily pressed.

FIG. 12 is a front view of the female mold 2 seen from the left in FIG.11.

Next, as shown in FIG. 13, the heating board 9 at the standby positionis moved to the front surface of the female mold 2. Thereafter, by theperipheral wall 14a of the holding frame 14 on the heating board 9, thepattern-bearing film X is pressed through the film suppressing frame 32.At this stage, the pattern-bearing film X is brought in contact with theperipheral wall of the heating board 9. Thus a closed heating space isformed, and the pattern-bearing film X is heated in a non-contact state.

After the pattern-bearing film X is satisfactorily softened, as shown inFIG. 14, it is subjected to a vacuum. Thus, the pattern-bearing film Xis caused to accord to the contour of the cavity surface 2a.

Thereafter, as shown in FIG. 15, the heating board 9 is retreated to thestandby position. Next, the female mold 2 and the male mold 2 areclamped. A molten resin is injected from the injection gate 4 so thatthe cavity is filled therewith.

After the molten resin is cooled and solidified, as shown in FIG. 16,the male mold 1 and the female mold 2 are opened and then the filmsuppressing frame 32 is separated from the film suppressing framefitting groove 2b on the female mold 2. Thus, a resin molding which isadhered to the pattern-bearing film X is taken out.

When the pattern-bearing film X is a transfer printing film, only thesubstrate film is peeled off with the pattern being left on the molding.

In another example of the method of opening the mold, when the moltenresin has been cooled and solidified, as shown in FIG. 17, the filmsuppressing frame 32 is moved from within the fitting groove 2b of thefemale mold 2 into the fitting groove of the male mold 1. After thepattern-bearing film X is released, the mold opening operation shown inFIG. 16 may be performed. In this method, the molding may be more easilytaken out from the male mold 1 and the female mold 2.

An effect intrinsic to the above-described embodiment is that since thepattern-bearing film X is fixed directly on the parting surface of thefemale mold and is thereafter heated and softened, deformation anddisplacement seldom take place on the pattern-bearing film X. Inparticular, when a pattern is to positionally coincide with the mold, ahigh positional accuracy is readily obtained.

In the above-mentioned embodiments, the transfer printing method wasdescribed. However, it should be noted that the present invention may beapplied to the laminate method.

In addition, in the embodiments, the panel heater which radiatesnear-infrared rays was used. Besides such a heater, an electric heater(which uses Nichrome coils and directly radiates Joule's heat of surfaceresistor or the like to the pattern-bearing film), a ceramic panelheater (which radiates far-infrared rays), or dielectric heating may beused. Moreover, as an example of heat transfer to the pattern-bearingfilm, radiant of infrared rays, electromagnetic wave, or the like may bedirectly used. Furthermore, air in the closed space may be heated so asto use heat transfer thereof to the pattern-bearing film X. Of course,both methods may be used.

As described above, according to the present invention, since thepattern-bearing film is preheated in a non-contact state, the heatingboard and the pattern-bearing film are not caused to contact. Thus,marks or impressions of through-holes of the heating board do not remainon the pattern-bearing film. As a result, these marks or impressions donot remain on the moldings.

Although the present invention has been shown and described with respectto best mode embodiments thereof, it should be understood by thoseskilled in the art that the foregoing and various other changes,omissions, and additions in the form and detail thereof may be madetherein without departing from the spirit and scope of the presentinvention.

What is claimed is:
 1. A method for forming a pattern onto an articleduring an injection molding thereof, comprising the steps of:providing apattern-bearing film in the form of a supply roll of a strip; supplyingthe pattern-bearing film from said supply roll to move the film to amolding position where a male mold and a female mold are opposed; movinga heating board to said molding position; holding only an outerperipheral portion of a part of said pattern-bearing film in saidmolding position in a set-apart but sealed relation to a heating surfaceof said heating board moved to said molding position with said heatingsurface spaced from the pattern-bearing film; thereafter cutting thepattern-bearing film at a position thereof displaced toward said supplyroll from said part where said film is held to the heating surface tothereby isolate said part from the rest of the film extending from saidsupply roll to said part; after said step of cutting, heating andsoftening said part of the pattern-bearing film by the heating boardwhile said set-apart but sealed relation is maintained; transferringsaid heated part of the pattern-bearing film onto an internal surface ofsaid female mold to contact said pattern-bearing film with said internalsurface; retracting said heating board from said molding position;clamping said male mold and said female mold while said heatedpattern-bearing film is in contact with said internal surface; andinjecting a molten resin into a cavity defined by said male mold andsaid female mold to form a molded article and to adhere saidpattern-bearing film to the surface of said article.
 2. The method ofclaim 1, further comprising the step of:holding said outer peripheralportion of said pattern-bearing film so that a closed heating space willbe formed between said pattern-bearing film and said heating surface ofsaid heating board.
 3. The method of claim 2, further comprising thestep of:supplying air at high pressure to said closed heating space totransfer said pattern-bearing film to the internal surface of saidfemale mold.
 4. The method of claim 1, further comprising the stepof:supplying air into a space between said heating surface and saidpattern-heating film to maintain the pattern-bearing film in a spacedparallel relation with said heating board.
 5. The method of claim 4,further comprising the step of:supplying air into said space through alarge number of air blowing holes provided in said heating surface. 6.The method of claim 1,wherein said holding step is performed between aholding frame fixed on said heating surface of the heating board and afilm suppressing frame for holding said pattern-bearing film.
 7. Themethod of claim 1, further comprising the steps of:feeding saidpattern-bearing film onto a parting surface of said female mold; holdingsaid pattern-bearing film over said parting surface; and heating saidpattern-bearing film held over said parting surface of said female mold,wherein said heating step is performed by said heating surface of saidheating board.